(IMO)
Think of Vanilla WoW. There were a lot of interesting things there. The whole hakkar thing, that was cool, although you had to do a bit of research to know what was happening. Ahn'Quiraj, that was pretty amazing as well, if you look up the War of the Shifting Sands on wowwiki. The Nefarian thing, with the Chromatic Dragonflight, that seemed awesome, and them fighting with the Dark Iron who summoned Ragnaros, who enslaved the Dark Iron, that was awesome as well. Naxxramas - Well that was a little bland but whatever. Burning Crusade - at the time it seemed awful. Space, spaceships, etc etc, but it set the stage for Wrath of the Lich King. It closes doors, such as Illidan, but it opens so many more. Him using Magtheridon as a resevoir of blood for Fel Orcs, that was great. The Alliance on Outland and Azeroth rekindling, finding out what had happened to them. The Horde, meeting their ancestors, Thrall meeting his grandmother, a ton of Orcs sons, such as Garrosh Hellscream. Also, the Naga didn't do much, but w/e. The Blood Elves, now that was pretty awesome. After Kael'Thas was killed, he was brought back to Kil'Jaeden and served him. They created Fel Elves. He tried summoning Kil'Jaeden, and don't get me started on the whole Anveena thing. Karazhan, that was interesting to see what happened there and we still have yet to find out why (the dungeon underneath Karazhan, anyone?) also the Dark Riders and the Scythe of Elune, I think that was Vanilla WoW but that was awesome too. The Netherwing Brood, I liked that. Now in Wrath of the Lich King it is full of lore. Garrosh Hellscream starting to revert to Old Horde ways and wanting to fight Thrall. The thing with the Lich King's heart, the Knights of the Ebon Blade, the Ashbringer, Tirion Fordring, etc etc etc. Mal'Ganis being alive, which I liked. Although Muradin being alive was retarded. Yogg-Saron corrupting Titan guardians, and soon being released. His presence is everywhere. Saurfang's son and Bolvar Fordragon dying at the Wrath Gate cinematic. The Undercity splitting apart, but I wish Varimathras wasn't eliminated so quickly. Wish he was a raid instant. In HoS, with Brann Bronzebeard, when you discover that stuff about the Titans was the most epic, perhaps, not many people seem to know about it
I haven't even mentioned Malygos yet, and with BC setting the stage the Nether Dragons Tyrygosa brought to the Nexus awoke Malygos. Dalaran, which was kind of eh but cool at the same time. I'm probably missing stuff too, but now that I think of it, WoW lore can be pretty good.
Think of Vanilla WoW. There were a lot of interesting things there. The whole hakkar thing, that was cool, although you had to do a bit of research to know what was happening. Ahn'Quiraj, that was pretty amazing as well, if you look up the War of the Shifting Sands on wowwiki. The Nefarian thing, with the Chromatic Dragonflight, that seemed awesome, and them fighting with the Dark Iron who summoned Ragnaros, who enslaved the Dark Iron, that was awesome as well. Naxxramas - Well that was a little bland but whatever. Burning Crusade - at the time it seemed awful. Space, spaceships, etc etc, but it set the stage for Wrath of the Lich King. It closes doors, such as Illidan, but it opens so many more. Him using Magtheridon as a resevoir of blood for Fel Orcs, that was great. The Alliance on Outland and Azeroth rekindling, finding out what had happened to them. The Horde, meeting their ancestors, Thrall meeting his grandmother, a ton of Orcs sons, such as Garrosh Hellscream. Also, the Naga didn't do much, but w/e. The Blood Elves, now that was pretty awesome. After Kael'Thas was killed, he was brought back to Kil'Jaeden and served him. They created Fel Elves. He tried summoning Kil'Jaeden, and don't get me started on the whole Anveena thing. Karazhan, that was interesting to see what happened there and we still have yet to find out why (the dungeon underneath Karazhan, anyone?) also the Dark Riders and the Scythe of Elune, I think that was Vanilla WoW but that was awesome too. The Netherwing Brood, I liked that. Now in Wrath of the Lich King it is full of lore. Garrosh Hellscream starting to revert to Old Horde ways and wanting to fight Thrall. The thing with the Lich King's heart, the Knights of the Ebon Blade, the Ashbringer, Tirion Fordring, etc etc etc. Mal'Ganis being alive, which I liked. Although Muradin being alive was retarded. Yogg-Saron corrupting Titan guardians, and soon being released. His presence is everywhere. Saurfang's son and Bolvar Fordragon dying at the Wrath Gate cinematic. The Undercity splitting apart, but I wish Varimathras wasn't eliminated so quickly. Wish he was a raid instant. In HoS, with Brann Bronzebeard, when you discover that stuff about the Titans was the most epic, perhaps, not many people seem to know about it
The reason the Titans didn't kill the Old Gods is because they are parasites, and Azeroth is their host. Humans were made by the Titans, along with the Vrykul. That dead Old God that is killed in Darkshore might be the reason half of Azeroth is missing.